Thank you for the update!
So another test of the 'EasyIcon.exe':
Loading and displaying a thumbnail of a random .jpg image works fine now
But even if I've set a 'Test.ico' before and the requester says, that it has saved a 'Test.ico' and a 'Test.icns' now, only the '.icns' file can be found in my HD directory...
If you want to offer both icon formats when saving (and not only the one, set in the stringgadet at the top of the EasyIcon tool), then maybe offering checkboxes for both formats are a good idea... so the user can adjust if he want to have .ico and/or .icns format